The role of metallic palladium in the reductive decomposition of π-allyl palladium chloride in aqueous alkaline solutions

Russian Chemical Bulletin -     

Divinyl Sulfoxide: XI. Selective Addition of Carbonodithioate Anions to Divinyl Sulfoxide in the Water-Benzene System

Selective monoaddition of carbonodithioate anions to divinyl sulfoxide gives rise to O-alkyl S-[2-(vinylsulfinyl)ethyl] carbonodithioates [ROC(S)SK, R = Et, Bu; 42–50°C, 6 h, NaHCO₃, aqueous benzene].     

Synthesis and electrochemical applications of fluorinated vinylazole copolymers for monitoring NO in model and biological systems

Copolymers of 1-vinyl-1,2,4-triazole and 5-vinyltetrazole with 1,1,5-trihydrooctafluoropentyl methacrylate and 1,1,7-trihydrododecafluoroheptyl methacrylate were prepared under the conditions of radical initiation. These copolymers were used for modification of the surface of a glassy carbon electrode, and the effect of the modification on the electrochemical behavior of the electrode in anodic oxidation of dopamine and NO was studied. The possibility of enhancing the selectivity of the electrochemical sensor for monitoring NO in biological media was demonstrated.     

Organoinorganic composites based on tetraethoxysilane and nitrogen polybases

Hybrid organoinorganic composites insoluble in water and organic solvents were prepared by the hydrolysis of tetraethoxysilane in the presence of poly-1-vinylpyrazole, poly-1-vinylimidazole, and poly-4-vinylpyridine. The composition of the composites was determined by the nature of the polymeric nitrogen base and hydrolysis conditions. The composites synthesized showed high sorption activity in the extraction of the [PdCl₄]^2?, [PtCl₆]^2?, and [AuCl₄]^? ions from hydrochloric acid solutions.     

Dehydrogenation of 1-(diphenylphosphinoyl)-2-(N′-phenylhydrazino)ethane and N-butyl-N′-phenylhydrazine

Dehydrogenation of 1-(diphenylphosphinoyl)-2-hydrazino-substituted ethanes and N-butyl-N′-phenylhydrazine to the corresponding hydrazone derivatives is performed. Both reactions were established to involve predominantly, if not exclusively, an azo intermediate.     

Evaluation of parameters critical to observing proteins inside living Escherichia coli by in-cell NMR spectroscopy

Our recently developed in-cell NMR procedure now enables one to observe protein conformations inside living cells. Optimization of the technique demonstrates that distinguishing the signals produced by a single protein species depends critically on protein overexpression levels and the correlation time in the cytoplasm. Less relevant is the selective incorporation of (15)N. Poorly expressed proteins, insoluble proteins, and proteins that cannot tumble freely due to associations within the cell cannot yet be observed. We show in-cell NMR spectra of bacterial NmerA and human calmodulin and discuss limitations of the technique as well as prospects for future applications.     

Influence Exerted by Pyrite Impurity in the Initial Graphite on Properties of Residual Graphite Hydrosulfates

The influence exerted by the particle size and the distribution of sol impurities in the initial graphite, and also by pyrite additives, on the properties of residual graphite hydrosulfates synthesized by oxidation in the CrO₃-H₂SO₄ system was studied.     

Photolysis of hexamethyldisilane at 206 nm

The photolysis of Me₆Si₂ at 206 nm results in two main decomposition processes: simple Si---Si bond breaking with a quantum yield of Φ = 0.21 ± 0.03, and Me₃SiH elimination with the concomitant formation of Me₂SiCH₂ with Φ = 0.18 ± 0.01. There is also a minor decomposition channel with a very small quantum yield, Φ = (5.6 ± 0.2) × 10⁻³, which results in the formation of Me₄Si and Me₂Si. The main fate of the excited Me₆Si₂ molecule produced during photolysis is stabilization by collisional deactivation. The end products observed indicate that the reaction pathways followed by the main intermediates, Me₃Si and Me₂SiCH₂, are the same as those found in the photolysis of Me₄Si (Ahmed et al., J. Photochem. Photobiol. A: Chem. 86 (1995) 33).     

Catalytic Properties of Acid Solutions and the Structure of Acid–Base Complexes with Strong Hydrogen Bonds

The catalytic action of acid solutions involves an equilibrium step in the formation of a reactive complex of reactant molecules with catalyst entities. The relative concentrations of these complexes are determined by using thermodynamic parameters (acidity functions and activities of catalyst components). Data on the structure of complexes with strong H-bonds can be obtained from the vibrational spectra of these species. These data are required for establishing the mechanisms of catalytic reactions and for predicting the catalytic properties of acid solutions containing these complexes.     

Formation of pyrrolo[2,3-f]quinolines from substituted 5-methyl-6-aminomoles by the combes reaction

It is shown that the reaction of 2, 3, 5-trimethyl-6-amino-indole with 1, 3-diketones is a convenient method for the preparation of angular IH-pyrrolo[2,3-f]quinolines, while the presence of a methyl group on the pyrrolic nitrogen atom of the initial indole as a result of steric hindrance completely blocks cyclization to the corresponding pyrroloquinolines.Mordovskii State Educational Institute, Saransk 430007. Moscow State University, Moscow 119899. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No 11, pp. 1499–1501, November, 1995. Original article submitted May 23, 1995.